ByJerome Delay and Melanie Gouby, Associated PressNovember 27, 2012

Goma, Congo — Congo's M23 rebels defied a deadline imposed by neighboring nations, saying Tuesday the insurgents will stay in the crucial, eastern city of Goma and will fight the Congolese army if it tries to retake it.

Congo's military spokesman Col. Olivier Hamuli called it "a declaration of war" and said the army will resume combat, although he declined to say when.

Highlighting the volatility of the situation, a different rebel group based in Congo, known as the FDLR, crossed into neighboring Rwanda and attacked Rwandan army positions, according to villagers, eyewitnesses and Rwanda's military spokesman. It raised the possibility that Congo was directly retaliating against Rwanda, its much-smaller but more affluent neighbor, which has twice gone to war with Congo and which is now believed to be directing the M23 rebellion.

Speaking in Goma on Tuesday, M23 president Jean-Marie Runiga said the rebels will not leave the city of 1 million which they seized a week ago. The deadline imposed by the International Conference on the Great Lakes Region for the rebels to depart was midnight Monday.

At the same time, Runiga said that the rebels would like to negotiate with the Congolese government. In April, when the rebellion began, the group initially said they wanted to revisit the March 23, 2009 peace accord which paved the way for the fighters to join the Congolese military. The group initially claimed that Congo had not held up its end of the bargain, failing to provide the fighters with adequate pay and proper equipment.

Congo has already said that they are willing to negotiate with M23 on the basis of the 2009 peace accord, but on Tuesday, Runiga said that they no longer want to talk about only that. "Lots happened between 2009 and 2012. It is better to tackle the root causes of the issue once and for all," he said.

He said that for the armed group to leave Goma, Congo is going to have to agree to a new set of conditions.

Runiga addressed reporters in the center of Goma, almost 12 hours after the midnight deadline for their retreat had passed. Female ushers led reporters to their chairs. All of them were wearing Mushanana fabric, a toga-like dress typically worn by Rwandan women. The visual detail emphasized the foreign provenance of the rebels now occupying Goma, who according to the findings of the United Nations Group of Experts are financed by Rwanda, which is providing them with arms, sophisticated communications equipment as well as several battalions of troops.

"They have refused to leave the city of Goma. This is a declaration of war, and we intend to resume combat," said Congo's military spokesman, Hamuli, whose troops have been pushed back to the town of Minova, 60 kilometers (36 miles) outside of Goma. Asked when, he said: "Arrangements are being made by the FARDC (the Congolese military) hierarchy."

The M23 was created nearly eight months ago by former rebels who joined, and then defected from the Congolese army. They have been accused of human rights abuses, including executions and forced recruitment of children.

In a worrying development, fighting erupted about 30 kilometers (18 miles) north of Goma in Kibumba, near the Rwandan at around 5 a.m., said an M23 officer and Kibumba residents.

Hours later AP journalists saw rebels believed to be FDLR, a group that is believed to have received financial support from Congo, retreating back into Congo from the border. About 100 M23 fighters were pursuing the fighters from the FDLR, the French acronym for the Democratic Forces for the Liberation of Rwanda.

Rwanda's military spokesman Brig. Gen. Joseph Nzabamwita confirmed that the FDLR attacked Rwandan positions on Tuesday at dawn. "The attack on Cyanzarwe, Bugeshi Sector on Rubavu district was carried out by two companies of FDLR fighters of about 150 men," he said. "We managed to repulse them and send them back to DR Congo while others dispersed into different directions," he said.

He said two of the attackers were captured and are currently undergoing questioning while the Rwandan forces have intensified patrols on the border with Congo.

Both the M23 and the FDLR rebel groups have their origins in the scars left by Rwanda's 1994 genocide. The perpetrators of that genocide were from the Hutu ethnic group, and 18 years ago, at the end of the 100-day massacre they fled across the border and took refuge in the jungles of eastern Congo. Their leaders regrouped under the banner of the FDLR, and have used Congo as a base to try to take back Rwanda. Numerous reports indicate that the FDLR was tacitly backed by Congo, which wanted to use them as a buffer against Rwanda.

By contrast the M23 are fighters who are mainly from the Tutsi ethnic group that was targeted for extermination during the genocide.